chapter 3 - RiuNet

GENERAL INTRODUCTION
faced with the difficult task of estimating correct and accurate sperm
motility values, researchers used an arbitrary scale of criteria usually
comprising of five categories (Pérez et al., 2000; Asturiano et al., 2005;
Peñaranda et al., 2010b). Nowadays, CASA systems are able to accurately
quantify a high number of sperm motility parameters, including some that
could be not detected by visual inspection. Although there are several
companies which market the product (Projectes i Serveis R+D S.L.;
Microptic S.L.; Hamilton Thorne, etc.), the parameters provided by the
system are almost identical. It is noteworthy that most of the parameters
provided by CASA systems have been positively correlated with fertilization
rates, so these computer systems have proven themselves to be useful
tools for assessing sperm quality in fish.
The most commonly used parameters for fish sperm analysis were revised
by Rurangwa et al. (2004). The percentages of motile (TM) and progressive
motile spermatozoa (PM) can provide a general overview about the quality
of the sperm sample. TM means any spermatozoa showing any movement
while PM is determined by the spermatozoa which swim in an essentially
straight line. High correlations have been reported between both
parameters and fertilization rates in some fish species (Table 2).
Table 2. Coefficients of correlation between fertilization rates and total (r 1 ) and
progressive (r 2 ) motility in some marine and freshwater species.
Species r 1 r 2 Reference
Clarias gariepinus 0.76 0.81 Rurangwa el al., 2001
Sparus aurata 0.59 - Beirão et al., 2011a
Hippoglossus hippoglossus 0.81 - Otessen et al., 2009
Takifugu niphobles 0.68 0.70 This thesis, Chapter 5
Pagrus major 0.77 - Liu et al., 2007
Oncorhynchus mykiss 0.73 - Liley et al., 2002
Cyprinus carpio 0.53 - Linhart et al., 2000
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